Cytokines are soluble, small proteins that mediate a variety of biological effects, including the induction of immune cell proliferation, development, differentiation, and/or migration, as well as the regulation of the growth and differentiation of many cell types (see, for example, Arai et al., Annu. Rev. Biochem. 59:783 (1990); Mosmann, Curr. Opin. Immunol. 3:311 (1991); Paul and Seder, Cell 76:241 (1994)). Cytokine-induced immune functions can also include an inflammatory response, characterized by a systemic or local accumulation of immune cells. Although they do have host-protective effects, these immune responses can produce pathological consequences when the response involves excessive and/or chronic inflammation, as in autoimmune disorders (such as multiple sclerosis) and cancer/neoplastic diseases (Oppenheim and Feldmann (eds.) Cytokine Reference, Academic Press, San Diego, Calif. (2001); von Andrian and Mackay New Engl. J. Med. 343: 1020 (2000); Davidson and Diamond, New Engl. J. Med. 345:340 (2001); Lu et al, Mol. Cancer Res. 4:221(2006); Dalgleish and O'Byrne, Cancer Treat Res. 130:1 (2006)).
IL-17A, IL-17F and IL-23 are cytokines involved in inflammation. Human interleukin-17A (also known as “IL-17A”) is a cytokine which stimulates the expression of interleukin-6 (IL-6), intracellular adhesion molecule 1 (ICAM-1), interleukin-8 (IL-8), granulocyte macrophage colony-stimulating factor (GM-CSF), and prostaglandin E2 expression, and plays a role in the preferential maturation of CD34+ hematopoietic precursors into neutrophils (Yao et al., J. Immunol. 155:5483 (1995); Fossiez et al., J. Exp. Med. 183:2593 (1996)). Human interleukin-23 (also known as “IL-23”) is a cytokine which has been reported to promote the proliferation of T cells, in particular memory T cells.
IL-17A and IL-17F share 55% identity (Kolls and Linden, 2004). In addition to their sequence similarity, both of these cytokines seem are produced by similar cell types, most notably activated, memory CD4+ T cells. See e.g. Agarwal et al., “Interleukin-23 promotes a distinct CD4 T cell activation state characterized by the production of interleukin-17” J. Biol. Chem. 278:1910-191 (2003); see also Langrish et al. “IL-23 drives a pathogenic T cell population that induces autoimmune inflammation” J. Exp. Med. 201: 233-240 (2005); and Starnes et al. “Cutting edge: IL-17F, a novel cytokine selectively expressed in activated T cells and monocytes, regulates angiogenesis and endothelial cell cytokine production” J. Immunol. 167:4137-4140 (2001).
While IL-17F shares sequence homology with IL-17A, there are key difference between these molecules. For example, IL-17F mRNA is detected in many different tissues (such as, liver, lung, ovary, fetal liver, mast cells and basophils) while IL-17A expression is mostly restricted to T cells. See Fossiez, F., et al., “T cell IL-17 induces stromal cells to produce pro-inflammatory and hematopoietic cytokines”, J. Exp. Med. 183(6):2593-2603, (1996); Toy, D. et al., “Cutting edge: IL-17 signals through a heteodimeric receptor complex”, J. Immunol. 177(1):36-39(2006). Additionally, IL-17F binds IL-17RA with a much lower affinity than IL-17A.
Moreover, both have been similarly implicated as contributing agents to progression and pathology of a variety of inflammatory and auto-immune diseases in humans and in mouse models of human diseases. Specifically, IL-17A and IL-17F have been implicated as major effector cytokines that trigger inflammatory responses and thereby contribute to a number of autoinflammatory diseases including multiple sclerosis, rheumatoid arthritis, and inflammatory bowel diseases.
Recently it has been shown that using a combination of an antagonist to IL-17A and an antagonist to IL-23, relapse was prevented in a mouse model of multiple sclerosis. See co-owned U.S. patent application Ser. No. 11/762,738, filed Jun. 13, 2007 and WIPO Publication Number 2007/147019, published Dec. 21, 2007. However, there is a need for treatment of inflammatory disorders that would antagonize not only IL-17A and IL-23, but also IL-17F. The demonstrated in vivo activities of IL-23, IL-17A and IL-17F illustrate the clinical or therapeutic potential of, and need for, antagonists of IL-23, IL-17A and IL-17F. Specifically, antibodies that bind to IL-23 and to IL-17A or IL-17F that inhibit the immunological activities of both IL-17A and IL-17F would possess such novel therapeutic qualities. The present invention serves this need by providing antagonist molecules, inlcduing antibodies and antibody fragments that bind IL-23 and IL-17A or IL-17F, including antagonists that are comprised on one molecule.